1. Field of the Invention
The present invention concerns an x-ray apparatus of the type having an x-ray radiator, an automatic exposure timer, and a laser range finder (distance meter) to detect the focus-patient separation between the x-ray radiator and a patient.
2. Description of the Prior Art
An x-ray apparatus of the above type is known from German OS 38 10 501. It is proposed therein to arrange a contact-less range finder near the x-ray radiator in order to measure the distance (FOBJ) between the x-ray radiator and the surface of the patient. The necessary incident dose power is subsequently determined using the measured distance. If one likewise considers the film-focus separation (FFA), which is a known quantity, the total separation between the surface of the patient and an x-ray film cassette can be determined. This known x-ray apparatus, however, does not enable the actual thickness of the patient to be determined. The necessary incident dose power therefore can be determined only approximately.
X-ray apparatuses, in particular surface body detector systems, possess in the majority of cases an exposure control or an automatic exposure timer. Conventional exposure controls have, for example, three measurement fields in order to produce x-ray exposures of the left or right extremities of the patient or of the central body. A disadvantage is that the measurement chambers are visible in the x-ray image, primarily in the exposure of thin subjects. This problem in particular occurs when obtaining x-rays of children, The artifacts thereby generated are perceived as disturbing by the radiologists and are therefore undesirable.